It also opens the door for chess and other games of skill, including bridge, poker and Scrabble, to be recognised as sports. In theory, they could even become Olympic events.

The change in the law, which follows decades of campaigning by fans supported by MPs and peers, was slipped through the Commons by cabinet office minister Ed Miliband, himself a devotee.

Chess is played by more than four million people in Britain and is second only to football in popularity. The game's image has become edgier recently after lurid allegations surrounding the suicide of junior chess champion Jessie Gilbert. There were also ugly scenes at the Turin Chess Olympiad last June when the Armenian grand master Levon Aronian was allegedly punched and shoved by British grand master Danny Gormally. The dispute centred around Australian grand master Arianne Caoili, who is described as the Anna Kournikova of chess.

Worldwide, 124 governments recognise chess as a sport but, until now, the UK has stubbornly resisted giving the game official recognition. But Mr Miliband, who made the change in the Charities Bill, which became law last month, said legal distinctions between physical and mental sporting activities were outdated. "The new definition extends to sports or games that involve mental as well as physical aspects," he said.

The change marks the end of a long battle. Tony Blair has been lobbied by scores of advocates, including Russian grand master Gary Kasparov, and a Parliamentary motion was put down demanding British chess players in international tournaments be given government funding.The UK's chess fraternity is now planning to apply for lottery money and other charity funding to support chess clubs around the country. The English Chess Federation says it will push for chess to be recognised as an Olympic sport.

"For years and years the chess world has been trying to get chess recognised a sport," said the federation's president Gerry Walsh. "Hitherto, a degree of physical exertion has been required for something to be recognised as a sport. But this change in the law means that every club in the county can apply for charitable status."

The Department of Culture, Media and Sport said it was up to Sport England to decide if chess clubs would be eligible for lottery cash.

"This is about helping sports clubs getting charitable status; we support this," a spokesman for the department said.